The present invention relates generally to inertia welding, and more particularly to a method and apparatus for reducing component vibration during inertia welding.
Inertia welding is a process in which one component is rotated about an axis and brought in contact with a second component. Frictional forces between the components heat up the interface between the components sufficiently that the components melt and a weld is produced at the interface. Depending on the geometry of the components, the friction between the components can also induce vibrations in the components thereby causing stresses in the components. For example, when portions of a gas turbine engine compressor spool are inertia welded, each portion is clamped at their respective rim to an inertia welding machine. One portion is rotated and brought in contact with the other portion. As the portions are welded, one or more bores of the spool may vibrate, deflecting axially with respect to the spool centerline thereby causing stresses in the webs of the spool adjacent the rims. These stresses can cause the components to fail during welding or prematurely during later use.
Conventionally, the vibrating portions of the components are clamped tightly to prevent or reduce deflections, thereby reducing the stresses. Although this method works well, the portions of the components that vibrate are not always accessible for clamping. For example, the bores of a compressor spool are not easily accessible for clamping. Accordingly, a method and apparatus for reducing vibration in inaccessible portions of components is needed.
Although damping materials exist which can be applied to components to reduce vibration, these materials are difficult to apply in inaccessible areas of the components. Further, components such as gas turbine rotors which spin at high velocities require that all of the damping material be removed from the components prior to use. Otherwise, the residual damping material will cause component imbalance and potentially component failure. However, removal of the residual damping material is particularly difficult when the material is applied to difficult to access areas of the component.